TIG welding titanium
At 35,000 feet in the air, there is no room for error when it comes to airplane fabrication. This makes the work of the welding operation at the Safran Nacelles Group in Burnley, England, critical.
The facility manufactures thin-gauge titanium components used in nacelles — the parts on an aircraft that protect the engine. The Burnley location is part of Safran, the world’s third-largest aerospace organization, which produces parts for customers across the globe.
“We work to a lot of internal standards with high quality requirements,” says Mark Durkin, the welding specialist who oversees weld quality at the Burnley plant. “Tolerances are very stringent.”
As part of those rigorous standards, the facility is accredited by NADCAP (National Aerospace and Defense Contractors Accreditation Program) and undergoes regular audits of their weld quality management systems.
“The welding quality side is a very big part of the business, especially when it’s aircraft components. We have a nondestructive testing site and everything does go through there to get inspected,” says Chris Hill, manufacturing manager. “What sets us apart from other suppliers is our work with thin-gauge titanium. Not many facilities can weld down to 0.4 titanium, so obviously our skillset and our welders support that skill.”
The titanium parts welded at the facility range from 0.4 millimeter to 1.6 millimeter in thickness. With material that thin, there is potential for weld distortion when heat input isn’t properly controlled.
The Burnley facility experienced issues with distortion on a specific component for one customer — resulting in added time for rework and higher costs for scrapped parts. They were able to solve the problem with a switch to the Miller® Dynasty 400 TIG welder, a continuation of their long-standing relationship with Miller welding power sources and the Dynasty family of machines.
Welding complex titanium parts
The Burnley facility has areas for sheet metal, pre- and post-production, welding, nondestructive testing, heat treatment and pressing. They make more than 200 different products that go to different areas of the operation.
In the welding operation, 90% of the parts being fabricated are 0.4-millimeter titanium. The facility uses mostly pulsed TIG welding due to the thinness of the titanium.
“The pulsed TIG allows us to lower the heat input, which then leads to less weld distortion,” Durkin says.
They aim to have zero welding rework in meeting customer quality and timeline requirements. The welding operation has 12 welding bays and employs 19 welders who qualify to international ISO 24394 standard.
“Because it’s so thin, we have to be really careful to not blow holes in the material and make sure we’re not getting any color in the weld,” says TIG welder Samuel Chadwick. “We get a stamp and put our name on every job, so you better make sure it’s perfect every time. We don’t want anything coming back to us.”
A solution to weld distortion
One specific component for a customer was causing issues due to the very tight geometric tolerance, the amount of welding required on the part and the area on the part where the welding was needed. There were problems with weld distortion, causing a lot of rework and parts being scrapped.
In an effort to fix the problems, the Burnley welding operation tested the Dynasty 400 TIG welder with that specific part. The Dynasty 400 provides a higher pulse rate for pulsed TIG welding — allowing operators to eliminate the weld distortion they were seeing with that part.
“The Dynasty 400 has a maximum of 5,000 pulses per second, compared to the other machine that has 500 pulses per second,” Durkin says. “The higher pulses allowed us to lower the heat and the distortion.”
Before switching to the Dynasty 400 for that part, the rework in the sheet metal operation was taking 45 minutes to an hour to remove the distortion on each part.
“We saw a massive time savings,” Durkin says.
It wasn’t only the time savings. Passing quality testing on the first try for each part helped them hit quality goals and reduce scrap waste and costs.
“We could hit first-time yield on every part rather than scrapping some off due to weld deformation,” Hill says. “That’s really key. If we have any scrap fallout due to a geometric issue, we’ve then got to replace that part through our production plan, so the Dynasty helped alleviate that problem.”
Miller Dynasty machines are a go-to welding power source for many in the aerospace industry because they offer high weld quality and arc control can be dialed in very tightly.
Easy-to-use TIG welders
The welders and managers at the Burnley plant have been very happy with the entire Dynasty family of welders that they have used for years at the facility, including the Dynasty 210 and Dynasty 400.
When they choose welding power sources for the operation, they look for machines that are easy to set up and use, are energy efficient, have the necessary power and duty cycle, and offer excellent reliability.
“We have seen many benefits using Miller Dynasty machines — everything from the interface that makes it easy for the welder to change settings between jobs to the excellent reliability and quality results,” Durkin says. “When we bring a new person in, there's very little training on the machine due to how user-friendly it is. So basically, the person can go straight into welding operations.”
Because the facility welds on a range of material thicknesses for some components, it’s important to have welding power sources that allow operators to easily change parameters or save welding programs for different components.
“We use complex jigs here at Safran,” says TIG welder Michael Whittaker. “With Dynasty welders, you can change the parameters very easily and very precisely, which is what you need in aerospace.”
And the similar interface among the different Dynasty models helps reduce training time for new welders.
“I’ve used different welders before and they’re very intimidating when you look at it. With the Dynasty, it’s formatted beautifully,” Whittaker says. “Everything is there. When I need to change something, it’s so simple.”
LCD display delivers information
Durkin sees the newly updated Dynasty 210 TIG welder fitting in nicely with the welding lineup used at the Burnley facility. The new interface on the Dynasty 210 features a color LCD display that provides visual feedback on how adjustments will affect the welding arc. This helps welders understand the arc and how it’s performing. The machine can also save up to 99 weld programs in memory and has a locks and limits feature that helps control welding parameters being used — to minimize deviation from the welding procedure specifications.
“With locks and limits, the welder is sure he’s welding with the correct parameters, and that hopefully helps us reduce scrap and potential rework,” Durkin says. “Also, for audit purposes, it allows us to show that he’s operating within specifications for each product.”
Relying on Miller TIG welders
In the years they have used Miller equipment at the Safran Burnley facility, they’ve never had a breakdown or downtime due to machine reliability issues. This helps the operation stay on time with customer projects and take on more work.
“That’s absolutely critical. We have a production plan to meet each week and when we have reliable equipment, it all goes toward hitting that plan,” Hill says. “We’ve had zero issues, zero downtime. We have tried alternatives from different suppliers and they have not met the quality standards. Every welding bay we have has a Miller welder in there.”